Fibre Length Loss across Recycling Loops and Score Cracking
Recycled fibre shortening and hornification limit bending strain, requiring wider matrix channels and virgin top layers to prevent score cracking.
Length Weighted Average Length
Statistical Measure
Mathematical calculations of wood pulp fiber dimensions emphasize the functional contribution of longer structural fibers by weighting individual fiber lengths by their own length. The calculation of length weighted average length multiplies each measured fiber length by its proportion of the total sample length rather than treating all microscopic particles equally. This measurement provides paper chemists and buyers with a reliable structural metric that correlates directly with paperboard physical performance.
The metric excludes non-structural dust and fines that would otherwise skew arithmetic mean calculations downward.
Sheet Optimization
Hardwood pulps typically exhibit values ranging between zero point seven and one point two millimeters, whereas softwood pulps deliver values between two point zero and three point two millimeters. Packaging board mills blend long softwood fibers into middle or outer plies to establish tear strength and runnability, while shorter hardwood fibers provide smooth printing surfaces and formation uniformity. Adjusting the ratio balances manufacturing costs against stiffness, burst resistance, and tensile energy absorption targets.
Measurement Condition
Automated optical fiber analyzers measure diluted pulp suspensions passing through high-resolution digital imaging flow cells. Polarized light sources and image analysis software identify individual fiber contours, curl indices, and kinking angles across tens of thousands of fibers per minute. Precise sample dilution prevents fiber bundling that would distort weighted calculations.